Scott McCoombe

Defining the Interaction of HIV-1 with the Mucosal Barriers of the Female Reproductive Tract

ABSTRACT Worldwide, HIV-1 infects millions of people annually, the majority of whom are women. To establish infection in the female reproductive tract (FRT), HIV-1 in male ejaculate must overcome numerous innate and adaptive immune factors, traverse the genital epithelium, and establish infection in underlying CD4+ target cells. How the virus achieves this remains poorly defined. By utilizing a new technique, we define how HIV-1 interacts with different tissues of the FRT using human cervical explants and in vivo exposure in the rhesus macaque vaginal transmission model. Despite previous claims of the squamous epithelium being an efficient barrier to virus entry, we reveal that HIV-1 can penetrate both intact columnar and squamous epithelial barriers to depths where the virus can encounter potential target cells. In the squamous epithelium, we identify virus entry occurring through diffusive percolation, penetrating areas where cell junctions are absent. In the columnar epithelium, we illustrate that virus does not transverse barriers as well as previously thought due to mucus impediment. We also show a statistically significant correlation between the viral load of inocula and the ability of HIV-1 to pervade the squamous barrier. Overall, our results suggest a diffusive percolation mechanism for the initial events of HIV-1 entry. With these data, we also mathematically extrapolate the number of HIV-1 particles that penetrate the mucosa per coital act, providing a biological description of the mechanism for HIV-1 transmission during the acute and chronic stages of infection.

Visualization of HIV-1 interactions with penile and foreskin epithelia: clues for female-to-male HIV transmission.

To gain insight into female-to-male HIV sexual transmission and how male circumcision protects against this mode of transmission, we visualized HIV-1 interactions with foreskin and penile tissues in ex vivo tissue culture and in vivo rhesus macaque models utilizing epifluorescent microscopy. 12 foreskin and 14 cadaveric penile specimens were cultured with R5-tropic photoactivatable (PA)-GFP HIV-1 for 4 or 24 hours. Tissue cryosections were immunofluorescently imaged for epithelial and immune cell markers. Images were analyzed for total virions, proportion of penetrators, depth of virion penetration, as well as immune cell counts and depths in the tissue. We visualized individual PA virions breaching penile epithelial surfaces in the explant and macaque model. Using kernel density estimated probabilities of localizing a virion or immune cell at certain tissue depths revealed that interactions between virions and cells were more likely to occur in the inner foreskin or glans penis (from local or cadaveric donors, respectively). Using statistical models to account for repeated measures and zero-inflated datasets, we found no difference in total virions visualized at 4 hours between inner and outer foreskins from local donors. At 24 hours, there were more virions in inner as compared to outer foreskin (0.0495 +/− 0.0154 and 0.0171 +/− 0.0038 virions/image, p = 0.001). In the cadaveric specimens, we observed more virions in inner foreskin (0.0507 +/− 0.0079 virions/image) than glans tissue (0.0167 +/− 0.0033 virions/image, p<0.001), but a greater proportion was seen penetrating uncircumcised glans tissue (0.0458 +/− 0.0188 vs. 0.0151 +/− 0.0100 virions/image, p = 0.099) and to significantly greater mean depths (29.162 +/− 3.908 vs. 12.466 +/− 2.985 μm). Our in vivo macaque model confirmed that virions can breach penile squamous epithelia in a living model. In summary, these results suggest that the inner foreskin and glans epithelia may be important sites for HIV transmission in uncircumcised men.

Reducing psychological distress and obesity in Australian farmers by promoting physical activity

BackgroundStudies have confirmed that the rate of mental illness is no higher in rural Australians than that of urban Australians. However, the rate of poor mental health outcomes, and in particular suicide, is significantly raised in rural populations. This is thought to be due to lack of early diagnosis, health service access, the distance-decay effect, poor physical health determinants and access to firearms. Research conducted by the National Centre for Farmer Health between 2004 and 2009 reveals that there is a correlation between obesity and psychological distress among the farming community where suicide rates are recognised as high. Chronic stress overstimulates the regulation of the hypothalamic-pituitary-adrenal (HPA) axis that is associated with abdominal obesity. Increasing physical activity may block negative thoughts, increase social contact, positively influence brain chemistry and improve both physical and mental health. This paper describes the design of the Farming Fit study that aims to identify the effect of physical activity on psychological distress, obesity and health behaviours such as diet patterns and smoking in farm men and women.Methods/DesignFor this quasi-experimental (convenience sample) control-intervention study, overweight (Body Mass Index ≥25 kg/m2) farm men and women will be recruited from Sustainable Farm Families™ (SFF) programs held across Victoria, Australia. Baseline demographic data, health data, depression anxiety stress scale (DASS) scores, dietary information, physical activity data, anthropometric data, blood pressure and biochemical analysis of plasma and salivary cortisol levels will be collected. The intervention group will receive an exercise program and regular phone coaching in order to increase their physical activity. Analysis will evaluate the impact of the intervention by longitudinal data (baseline and post intervention) comparison of intervention and control groups.DiscussionThis study is designed to examine the effect of physical activity on psychological health and other co-morbidities such as obesity, impaired glucose tolerance, hypertension and dyslipidaemia within a high-risk cohort. The outcomes of this research will be relevant to further research and service delivery programs, in particular those tailored to rural communities.Trial registrationACTRN12610000827033

The extracellular matrix in cancer progression: Role of hyalectan proteoglycans and ADAMTS enzymes

Remodelling of the extracellular matrix (ECM) has emerged as a key factor in cancer progression. Proteoglycans, including versican and other hyalectans, represent major structural elements of the ECM where they interact with other important molecules, including the glycosaminoglycan hyaluronan and the CD44 cell surface receptor. The hyalectan proteoglycans are regulated through cleavage by the proteolytic actions of A Disintegrin-like And Metalloproteinase domain with Thrombospondin-1 motif (ADAMTS) family members. Alteration in the balance between hyalectan proteoglycans and ADAMTS enzymes has been proposed to be a crucial factor in cancer progression either in a positive or negative manner depending on the context. Further complexity arises due to the formation of bioactive cleavage products, such as versikine, which may also play a role, and non-enzymatic functions for ADAMTS proteins. This research is providing fresh insights into cancer biology and opportunities for the development of new diagnostic and treatment strategies.

Cardiovascular risk factors and psychological distress in Australian farming communities

OBJECTIVE To examine the prevalence of cardiovascular disease (CVD) risk factors, psychological distress and associations between physical and mental health parameters within a cohort of the Australian farming community. DESIGN Cross-sectional descriptive study. SETTING Farming communities across Australia. PARTICIPANTS Data of men (n = 957) and women (n = 835) farmers from 97 locations across Australia were stratified into categories based on National Cholesterol Education Program guidelines. MAIN OUTCOME MEASURE(S)   Prevalence of and interrelationship between overweight, obesity, dyslipidaemia, hypertension, diabetes risk and psychological distress. RESULTS There was a higher prevalence of overweight (42.5%, 95% confidence interval (CI), 34.2-50.8), obesity (21.8%, 95% CI, 18.3-25.3), abdominal adiposity (38.4% 95% CI, 24.5-52.5), hypertension (54.0%, 95% CI, 34.4-73.5) and diabetes risk (25.3%, 95% CI, 17.7-36.7) in the farming cohort compared with national data. There was also a positive significant association between the prevalence of psychological distress and obesity, abdominal adiposity, body fat percentage and metabolic syndrome in older (age ≥ 50 years) participants. CONCLUSIONS This study group of farming men and women exhibited an increased prevalence of CVD risk factors and co-morbidities. The findings indicate a positive association between psychological distress and risk for developing CVD, particularly in the older farmers. If the younger cohort were to maintain elevated rates of psychological distress, then it is foreseeable that the next generation of farmers could experience poorer physical health than their predecessors.

Chest pain in rural communities; balancing decisions and distance

Objective: This pilot study examines the prevalence of cardiac risk factors in a cohort of agricultural workers, assesses their knowledge of local emergency health services and investigates their decision‐making abilities with regard to when and how they would seek help when experiencing chest pain.

Farmers with acute chest pain are uncertain how and when to seek help : A pilot study

Objective: This pilot study examines the prevalence of cardiac risk factors in a cohort of agricultural workers, assesses their knowledge of local emergency health services and investigates their decision‐making abilities with regard to when and how they would seek help when experiencing chest pain.

Short-chain fatty acids increase expression and secretion of stromal cell-derived factor-1 in mouse and human pre-adipocytes

OBJECTIVEStromal cell-derived factor-1 (SDF-1) is expressed in pre-adipocytes but its role is unknown. We investigated butyrate (a histone deacetylase inhibitor — HDACi) and other short-chain fatty acids (SCFA) in the regulation of SDF-1. We further investigated whether effects of SCFA were signalled through G protein-coupled receptors FFA2 and FFA3.DESIGN AND RESULTSSDF-1 mRNA expression and protein secretion were studied in 3T3-L1 cells and human pre-adipocytes. SDF-1 was abundant, with mRNA and protein levels increased by butyrate. This was replicated with acetate and propionate, but not with trichostatin or valproate. Trichostatin inhibited SDF-1 secretion. Pertussis toxin blocked stimulation by butyrate. The order of potency of SCFA in stimulating SDF-1 (C3 > C4 > C2) is consistent with action through FFA3. Silencing the FFA3 gene abolished butyrate-stimulated SDF-1 expression and secretion. FFA3 was expressed in both pre-adipocytes and adipocytes, while FFA2 was expressed in adipocytes only. SDF-1 expression was low in murine macrophage J774.2 cells, while the SDF-1 receptor CXCR4 was absent from 3T3-L1 cells but abundant in J774.2 macrophages. In human pre-adipocytes, FFA3 was also expressed and SCFA increased SDF-1 secretion.CONCLUSIONSSDF-1 and CXCR4 may mediate the interaction between adipose stromal cells and macrophages. Effects of SCFA are mediated through FFA3, but not histone deacetylase inhibition.

Nutrition Practice and Knowledge of First-Year Medical Students

Objectives. To compare the knowledge of Australian dietary recommendations to the dietary practices of first-year medical students. Design. Over a period of four years, anonymous online surveys were completed by medical students attending a first-year nutrition lecture. Background. There is little information on the nutritional knowledge and dietary practices of medical students. Setting. First-year postgraduate university medical students, Geelong, Victoria, Australia. Participants. Between the years 2012 and 2016, 32%–61% of first-year students completed the survey. Phenomenon of Interest. Student’s knowledge of dietary guidelines and related practices. Analysis. The frequency of response was assessed across the different year cohorts using descriptive statistics. Results. Between 59% and 93% of first-year students correctly identified the recommended daily servings for fruit, and between 61% and 84% knew the vegetable recommendations. In contrast only 40%–46% met the guidelines for fruit and 12%–19% met the guidelines for vegetables. Conclusions and Implications. Discrepancies between students’ nutrition knowledge and behavior can provide learning opportunities. With low rates of fruit and vegetable consumption in medical students, increased awareness of links between nutrition and health, together with encouragement to make behavioral changes, may increase the skills of graduates to support patients in improving dietary intake.

OA011-02. Defining the mechanisms of HIV entry and interactions with the female genital tract

Background To date, little is known about the mechanisms of the sexual transmission of HIV and how the virus interacts with the female genital epithelium to gain access to underlying target cells. We illustrate that HIV is able to penetrate both intact columnar and squamous epithelium in explants and the living rhesus macaque. Through a series of approaches we were able to determine the mechanism of HIV entry into these tissues.